Technical Living with 6v--How is it, really?

I just got a new car, 51 Hudson Hornet. It looks like someone started a 12v conversion on it, maybe 30 years ago. It has an alternator, but still the 6v coil, and looks like the old light bulbs also. The wiring is mostly original, with some patching done long ago.

The car has overdrive. I'm a bit leery about trying to run the OD on 12v, as the solenoid is a 6v version, and I don't want to burn it up.

Anyways...I know there are still some folks driving old cars with 6v systems. I just was wondering, how it works out these days? I can get a 6v battery at Tractor Supply for a hundred bucks, vs a 12v battery at walmart for $50. I don't have a generator or regulator, so I'd have to find one, or else spring for one of the new 6v alternators they sell (which would probably be the smart way to go).

I know generators and mechanical voltage regulators still give as much trouble as they used to, as I've had them on a couple other cars recently.

Thoughts?

 

First thought is that you could drop the voltage down to 6 for the overdrive.

Second thought is “old wiring that some one messed with a while back” makes me want to rewire it 6 or 12

 

Plan on buying a new battery once a year. The new ones are trash.
Some people have luck with Optima 6V, but they're ugly as the day is long
I ran 6V for about 4 years before giving up on it. Batteries would die over the winter, and once or twice they went stone dead on me, leaving me stranded. Wanna jump my 6V with your 12V massively electronic 2019 car? Didn't think so.
Plenty of people beat their chest and proclaim 6V is just as good as 12, you just need to make sure you have thick 00 battery cables, clean grounds and a litany of other "and also.."s
12 volt is the way to go.

 

Jim, I am sure that you already know this, but an alternator can work at any voltage. If you wanted to, you could make your own regulator to control the alternator at 6 volts. That might be a better and less expensive answer to your problem. There are plenty of voltage regulator circuits on the internet, and I am certain I have some circuit information here, if you choose to build one yourself.
I have built regulators to control an alternator at 24 volts, and it worked long after I sold the vehicle.
Regarding the 6 volt solenoid on the OD unit, three possibilities occurred to me.
Firstly, why not do a voltage drop, by adding a resister in the wire to the solenoid? Just figure out how much current it draws, and add the appropriate resister with a high enough wattage rating to handle the current.
Secondly, I have not done it with a new type battery, but why not just tap in to the battery at the 6 volt potential? In that way, you could run the rest of the car on 12 volts, you don't have to do anything fancy to keep the battery properly charged.
The other thought I had is, considering the fact that a lot of OD units were built by Borg Warner, is it possible to find a 12 solenoid off a different unit that would replace the 6 volt unit?
Bob

 

I've owned my car for 5 years. I put 10,000 miles on it in that time. Last year was about 5,000. It is still 6 volt. I replaced the battery one time. Though I did that thinking it was causing an issue, when in turn it was actually the generator. Had the generator rebuilt once and voltage regulator adjusted. Other than that, it has been fine. I don't even disconnect the battery or put a tender on it in the winter and it starts right up every spring

 

I have both 6V and 12V cars. 6V starts harder and lights are dimmer. But both cars everything works and functions as should and charge well, so I put them in the "if it aint broke, don't fix it" camp. Finding reliable 6V generator and regulator should be easy, the cars I have converted to 12V I have troubles with generators and voltage regulators. Batteries I put in the basement over our cold winters and they have lasted the last 3 years fine.

If the OD is a Borg warner unit, you can install a 12V solenoid, but they are very expensive. Like mentioned above you could put a voltage drop on the electrical part of the OD.

 

I had a buddy who had a dual carb ‘51 Chevy truck that commuted an hour each way a day through traffic, up and over a hill with 6v, vacuum wipers and bias plies and the only thing he changed eventually was going to radials because he wore out the Firestones quickly commuting.

It can be done, but you have to be dedicated and pretty hardcore to do it. The truck had been gone through and was kept in top mechanical condition.

 

If 6V 'is just as good' as 12V, why did Detroit totally abandon it in the '50s? As pointed out, 6V stuff is now rare and like many other obsolete systems, quality bits for it even rarer.

Bite the bullet and get a 12V OD solenoid, finish the 12V conversion....

 

Jim if I had everything or could lay my hands on everything easy enough to run it @6V it would not bother me in the least. I am not currently running 6V but I have run it in a daily here summer and winter. It gets damned cold here.

The down side to running 6V in my estimation is that electrical components are not readily available and you cannot run high output accessories. But if you can find one it will run an FM conversion on your radio well enough. You do have to keep things up to par, 6V is not as forgiving as 12V.

 

>> "I'm a bit leery about trying to run the OD on 12v, as the solenoid is a 6v version, and I don't want to burn it up."

The solenoid is an inductive load, that will quickly reach steady state current draw. Probably start with a 6 Volt source to measure the steady state current. Then you can calculate approximate power used. Then scale up for about a 7 Volt s (i.e. charging voltage) to size your power dissipation (you will need to drop 1/2 of the 14 Volts available from the battery/alternator.

Maybe get a quick estimate of current draw by measuring the solenoid resistance and applying Ohm's Law.

 

My daily driver is usually my 6 volt, 1931 Dodge coupe. I have no problems at all with the electrical system. I DID have a slight under the dash fire a while back, but that was my own fault. I have a new wiring harness from Rhode Island Wiring and all is good.

 

The basic rule of thumb (if one is not sure how much it will take) is +/- 10%. So if it is rated @6V it would be 6.6 or 5.6V. Its just a solenoid and may be more forgiving than that but that is the basic voltage you are looking at. It may actually be rated at a higher voltage than that. One would probably not be lucky enough to find the actual rating of said solenoid, and even if it had a nomenclature tag on it the lettering is most likely gone by now.

 

I am still running 6 volt in my 37 Chevy pickup. As long as everything is up to snuff it will work fine. Make sure that you have heavy enough battery cables, I get 3 years out of a battery. The only downside is the brightness of the lights but they have 6 volt LED's now but I haven't switched to them yet.

 

You can still buy 6V quartz Halogens too. Some of the guys who bring old Harleys for me to tune are still running 6V and running halogen conversions.

 

I have two cars on 6V & don't have any problems even on the fresh hi-dollar flatty I jus did. I have been using optima batteries both 6 & 12 V without any problems. You can find 6v parts just takes some searching around. Skip Haney in Fla will redo your coil with new stuff & Bubba can do the dizzy. Lot of good clean grounds . My plug wires will throw a blue & orange spark close to 1/2 " all stock stuff.

 

I think the dim headlights look cool!

 

Yep....cool, but dangerous. One can always get the reflectors redone by Uvira. They do awesome work.

 

As a past owner of an Auto Electric Rebuild shop( that is still in business) we rebuild 6v generators all the time and have the parts in stock. My Son owns it now. The shop has one of the few dynamic generator voltage regulator testers that allows testing under load and hot adjustments...so there is no question about the regulators ability to function properly in the vehicle at operating temp. If you have a unit you want to send in for rebuilding or restoration call: 509-453-8275 Smith Auto Repair and Electric...ask for Matt...tell him his Dad said to call...


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Used to have a 48 AD pickup. It was a rat before rat rods came about. 1 dead cell in battery so 4v. Had to push start 1st time in the a.m. after that it started 80% of the time off battery. No oil filter and the oil stayed clear as honey from one change to the next. Every window was broke and you could see the road go by thru the floor board. Ah, youth.

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Might sound good in theory, but in reality when you put a "extra" load on half the battery the other half has to be overcharged by that amount to get the whole battery charged. It is an easy solution, but counted in shortened battery life it may be an expensive one.

A resistor of the same resistance as the solenoid will split the supply voltage evenly between the ballast resistor and the solenoid. Just make sure the resistor can handle the current and you're good to go.

As for keeping an old system with previous owner modifications vs. rewiring it, the rewiring would be tempting. Previous owners are some of the most stupid people around, judging by many of their "repairs".​

 

Good to know, I am in Spokane

 

I would agree, if we were talking about using a lot of power out of the one side, but the draw on the one side would be minimal. The Diesel Toyota Landcruiser used a split 24/12 volt system, and I had one for approximately 8 years and did not experience any battery or other electrical problems.
Lead acid batteries can take a ton of abuse. Even though the construction of the plates in the modern batteries is not as robust as the older batteries, it is the improper maintenance that kills them, not the heavy use.
Bob

 

I am old...Prestolite made a battery Gp 27 size that was called a 6-12. It had three posts...one was ground, one was 12v and one was 6v. We used them in the old straight 8 Packards that were notoriously hard starting using 6v when hot...the 12v post supplied voltage directly to the switch on the starter and from that point on there were no issues. We also used to have a 6v/12v series/parallel switch but to make that work we had to add a second 6v battery. Cool stuff!


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The shop is in Yakima...been there for over 70 years...


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I have a 53 Willys jeep that was 6 volt. After 9 years the 6 volt battery finally died and I converted it to 12 volts. Now the Halogen headlights are much brighter than the old 6 volt ones, and it spins so fast with the 6 volt starter on 12 volts that it is instantly running. Anyone gets in my way, (not likely with the original 4 cylinder engine) the 6 volt horn on 12 volts blows them away. My 49 Buick with the Cad 472 was converted to 12 volts with home made Runtz voltage reducers for the gauges. Works great. So.... you need to decide, do you want to go through some stuff now, too make repairs in the future easier, or do you want to stay stock. Your choice Squirrel, they both work, just one is easier to get parts for, sound systems easier, not to mention charging your cell phone.

 

We had a very active Jeep Club in the Northwest where I used to live and we converted a lot of Jeeps to 8v systems...all the 6v components stayed the same and we just adjusted the regulator to 9.2v and life was good.


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The Runtz voltage reducers for gauges work well.


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Thanks for all the replies! There's more to it than just the OD for me wanting to leave it 6v. I got this car for an upcoming road trip, that gets points (World Tour of Texas). Having things go wrong is a bonus, and leaving it 6v would be better for that.

I expect I'll go ahead and make it 12v, and see how it goes. I might have a 12v solenoid available, and if not I can do the math and figure out how to keep the 6v one alive.

I wasn't sure about the lights not being changed yet, but I just pulled a headlight loose and confirmed, 6006 part number on the newer of the two sealed beams.

btw this is the lucky car

 

I saw a YouTube video earlier this week, a guy named Jonathon that does the "first start in ..... years" thing and he was using one of the 6-12 batteries like theboss20 was mentioning. Starter was the only thing running on the 12 volt side. Pretty cool setup. I'll see if I can find the link.

Edit: Here is the link. The battery thing starts about 6:45

 

my car is still 6 v pos ground. my batteries last for 5 to 7 years I buy group one batteries from the Exide warehouse, Keep my genny tuned up and lubricated, the key to six volt systems in proper gauge wires, when in doubt go bigger, keeping resistance to a minimum, and clean tight grounds. A ground strap from the body to the engine or frame will help with all six volt accessories and lights. As far as light brightness is concerned, watts are watts a 55 watt 6v low beam should have the same output as a 55 watt 12 v lamp. if I want GPS, or Music in the car I power it with my 12v jumper pack goes nearly three days without a recharge. We generally go on one long trip or tour every season and have not once ben let down by the 6 volt system. hard starting? tune the car properly, dim dash bulb clean or replace the bulbs.

As far as the overdrive goes the battery relay power side wires need to be 10 g or maybe even do a double strand, for the switch side of the relay 12 is a good way to go, if its a Borg Warner the solenoid is gonna want 20/25 amps so 25/30 amp fuse at the relay for the pull in circuit and 10/15 for the hold in. the power from the relay to the solenoid should be as short as possible and 10 gauge or better. the kick down switch circuit can go 12 gauge. the governor functions to complete the ground circuit for the solenoid at preset speed, so again good, tight, clean connections with lots of di electric grease to keep them protected from the weather, grounded to a good clean chassis connection.

Rule of thumb heavy loads like horns headlamps stop lights, heater, fog lamps, radio, 10 gauge, medium loads running lights interior courtesy lighting 12. parking lights license light trunk or under hood instrument lights can go 14. 16 gauge has no place in a 6 volt car. Main battery cables I use braided ground strap, and 0 gauge primary cable for the negative post to the starter solenoid, same for solenoid to starter, for the body ground I run a 12 volt battery cable with flat connection on both ends, going from the firewall to the bell housing.

A lot of engineering went into these systems and they worked as designed till people suddenly couldn't understand why their whimpy 12 volt battery cable got hot with poorly tuned engine not starting. or they wanted portable disco lounges. by the way nice Hudson! you gonna paint it or try to polish it out? bet that paint will cut and shine up nicely.